RETScreen Combined Heat and Power Cogeneration (Santosh)

7/28/2019 RETScreen Combined Heat and Power Cogeneration (Santosh)

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RETScreen Combined Heat andPower

(Cogeneration) Projects

Photo Credit: Warren Gretz, DOE/NREL PIXPower Plant


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Objectives

Review basics of Combined Heat and Power

(CHP) Systems

Illustrate key considerations

for CHP project analysis

Introduce RETScreen

CHP Project Model


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Electricity

Heat

Buildings

Communities

Industrial processes

but also

Increased energy efficiency

Reduced waste & emissions

Reduced T&D losses An opportunity to use district

energy system

Cooling

What do Combined Heat andPower (CHP) systems provide?

Photo Credit: Andrew Carlin, Tracy Operators/NREL PIX

Biomass Fired Power Plant, USA


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CHP System Motivation

Traditional central power system is inefficient

One-half to two-thirds of energy is wasted as heat

This heat, otherwise lost,

can be used for industrial

processes, space andwater heating, cooling, etc.

Electricity is typically

more valuable than heat

Adapted from World Alliance for Decentralized Energy; Units in TWh


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The CHP Concept

Simultaneous production of two or more types of usable energy froma single energy source (also called Cogeneration)

Use of waste heat from power generation equipment


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CHP DescriptionEquipment & Technologies

Power equipment Gas turbine

Steam turbine

Gas turbine-combined cycle

Reciprocating engine

Fuel cell, etc. Heating equipment

Waste heat recovery

Boiler / Furnace / Heater

Heat pump, etc.

Cooling equipment Compressor

Absorption chiller

Heat pump, etc.

Photo Credit: Rolls-Royce plc

Gas Turbine

Photo Credit: Urban Ziegler,NRCan

Cooling Equipment


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CHP Description (cont.)Fuel Types

Fossil fuels Natural gas

Diesel (#2 oil)

Coal, etc.

Renewable fuels

Wood residue

Biogas

Agricultural byproducts

Purpose-grown crops,

etc. Bagasse

Landfill gas (LFG)

Geothermal energy

Hydrogen, etc.

Photo Credit: Joel Renner, DOE/ NRELPIX

Geothermal Geyser

Photo Credit: Warren Gretz,

DOE/NREL

Biomass for CHP


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CHP Description (cont.)Applications

Single buildings Commercial and industrial

Multiple buildings

District energy systems (e.g.

communities) Industrial processesLFG CHP for district heating system, Sweden

Photo Credit: Urban Ziegler,

NRCan


NRCan

Micro turbine at greenhouse


NRCan

CHP Kitchener City Hall


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Heat from a CHP plant can be distributed to multiple nearbybuildings for heating and cooling

Insulated steel pipes are buried 0.6 to 0.8 m underground

Advantages compared to each building having own plant:

Higher efficiency

Emissions controls

on single plant

Safety

Comfort

Operating convenience

Initial costs typically higher

District Energy Systems

Photo Credit: SweHeat

District Energy Plant


District Heat Hot Water Pipes


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CHP System Costs

Costs highly variable Initial costs

Power generation

equipment

Heating equipment

Cooling equipment

Electrical

interconnection

Access roads

District energy piping

Recurring costs

Fuel

Operation & maintenance

Equipment replacement & repair


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CHP Project Considerations

Reliable, long-term supply of fuel

Capital costs must be kept under control

Need customer for both heat and power

Must negotiate sale of electricity onto grid if not all consumed on-

site Typically plant is sized for heating base load (i.e. minimum heating

load under normal operating conditions)

Heat output typically equal to 100% to 200% of the electricity

output

Heat can be used for cooling through absorption chillers

Risk associated with uncertainty of future

electricity / natural gas (spark) price spread


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Example: Canada

Single Buildings

Buildings requiring heating,

cooling, and a reliable power

supply

Hospitals, schools, commercial

buildings, agricultural buildings,etc.

Reciprocating Engine

Photo Credit: GE Jenbacher

Exhaust Heat Recovery Steam Boiler


Hospital, Ontario, Canada



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Examples: Sweden and USA

Multiple Buildings

Groups of buildings served by a central heating/cooling power plant Universities, commercial complexes, communities,

hospitals, industrial complexes, etc.

District energy system

Turbine used at MIT, Cambridge, Mass. USA


District Energy Plant


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Example: BrazilIndustrial Processes

Industries with a high, constant

heating or cooling demand are good

candidates for CHP

Bagasse for Process Heat at a Mill, Brazil

Photo Credit: Ralph Overend/ NREL Pix

Also applicable to industries

that produce waste materialwhich can then be used to

generate heat and power


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Examples: Canada and Sweden

Landfill Gas

Landfills produce methane

as waste decomposes

This can be used as the fuel

for cooling, heating or

power projects

LFG CHP for district heating system, SwedenPhoto Credit: Urban Ziegler,

NRCan

Photo Credit: GazMetropolitan


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RETScreen

CHP Project Model

World-wide analysis of energy production, life-cycle costs

and greenhouse gas emissions reductions

Cooling, heating, power, and

all combinations thereof

Gas or steam turbines,

reciprocating engines, fuel cells,boilers, compressors, etc.

Vast range of fuels, ranging from

fossil fuels to

biomass & geothermal

Variety of operating strategies

Landfill gas tool

District energy systems

Also includes:

Multiple languages and currencies,

unit switch, and user tools


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RETScreen CHP Project Model (cont.)

Capabilities for various type ofprojects

Heating only

Power only

Cooling only

Combined heating & power

Combined cooling & power

Combined heating & cooling

Combinedcooling, heating & power


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RETScreen

CHP Project ModelHeating Systems


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RETScreen

CHP Project ModelCooling Systems


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RETScreen

CHP Project ModelPower Systems


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RETScreen

CHP EnergyCalculation

Simplified CHP Energy Model Flowchart

l lid i f h


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Example Validation of the

RETScreen

CHP Project Model

Overall validation by independent consultant (FVB Energy Inc.) and bynumerous beta testers from industry, utilities, government and academia

Compared with several other models and/or measured data, with excellent

results

(e.g. steam turbine performance calculations compared with GE Energy

process simulation software called GateCycle)

Kpph = 1000 lbs/hr

Steam Turbine Performance Calculation ComparisonRun Inlet Flow,

P, T

Kpph/psia/F

Outlet Flow

P, T

Kpph/psia/F

Extract Flow,

P, T

Kpph/psia/F

Efficiency GateCycle

Power Output

MW

RETScreen CHP

Power Output

MW

1 50/1000/750 40/14/210 10/60/293 80% 3,896 3,883

2 50/1000/545 50/60/293 0 80% 2,396 2,404

3 50/450/457 50/60/293 0 80% 1,805 1,827

4 50/450/457 50/14.7/212 0 81% 2,913 2,915


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Conclusions

Combined Heat and Power (CHP) systems make efficient use

of heat that would otherwise be wasted

RETScreen calculates demand and load duration curves,

energy delivered, and fuel consumption for variouscombinations of heating, cooling and/or power systems using

minimal input data

RETScreen provides significant preliminary feasibility studycost savings


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Thank You

Combined Heat and Power Project Analysis ModuleRETScreen

International Clean Energy Project Analysis

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RETScreen Combined Heat and Power Cogeneration (Santosh)

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